MIME Encapsulation Depth ?

All,

Is it possible with Exiscan to know how deeply nested an rfc-2822
attachment (or any other MIME container) is within the ACL
acl_smtp_mime ?

>From time to time we are the recipient of mail loops whereby two
(broken) mail servers keep sending each other bounce messages (usually
from/to postmaster) including the offending original message as an
attachment. As such our Exim4+SA+ClamAV setup is the recipient of
progressively larger and larger nested MIME emails.

I'd like to be able to reject an email if the nesting gets ridiculously
deep. Based on the docs I can know the current mime part number and if
it's an rfc-2822 attachment, but not apparently if this attachment is
itself part of another attachment. 

Has anyone tried this already, or is this something I should ask to be
wishlisted ?

Thanks,
Jerry.
-- 
Jerry Nicholls                       E: [email protected]
Core & Network Operations Manager    W:            http://www.zen.co.uk/
Zen Internet Ltd.                    T:                    0845 058 9000
                                     F:                    0845 058 9005